Most of the agents useful in inhibiting the growth of malignant tumor cells discovered to date have either been alkylating agents, of the nature of the nitrogen mustards, or anti-metabolites for vitamins and nucleic acids, such as 8-azaguanine, 5-fluoronicotinic acid, and the like. Recently a group of novel alkaloids, obtainable in pure form from the plant Vinca Rosea, have been found to be particularly valuable in the treatment of leukemias and have even shown some activity against various solid tumors. These alkaloids have a chemical structure which is totally unrelated to any known anti-tumor agent, and they apparently act in a manner distinctly different from such other agents.
It is an object of this invention to provide a method of inhibiting the growth of malignant tumor cells in mammals, specifically mice, which method employs a previously known alkaloid not related structurally to the Vinca alkaloids and having a quite different anti-tumor spectrum when compared with that of any of the anti-tumor agents heretofore known.